Refrigeration apparatus



Jan. 2, 1945. G. s. MGCLOY 2,366,635

REFRIGERATION APPARATUS Filed Jan. 7, 1942 FIG- 2.

INVENTOR GRAHAM 5. M 620V I VATTOR EY Patented Jan. 2, 1945 Graham S. McCloy, Springfield, Mass, assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application January 7, 1942, Serial No. 425.875

12 Claims. '(Cl. 62-4) This invention relates to refrigeration apparatus and more especially to a means for defrosting the cooling unit of such apparatus.

Referigerating apparatus comprising a cooling unit compensated to maintaining the temperature of a refrigerated chamber approximately constant in varying ambient temperatures such as the apparatus shown in Patent No. 1,886,042 issued to F. H. Osborne on November 1, 1932, presents difficulties in defrosting the cooling unit.

In such apparatus, the ordinary defrosting device comprising an additional bias on the temperature-responsive element of the thermostat such as shown in Patent No. 2,035,291 issued to J. J. Bauman On March 24, 1936, is not practical. The

reason for this is that the cooling unit varies in temperature inversely with the temperature ambient th refrigerated chamber and a fixed bias imposed on the temperature-responsive element would not necessarily hold the temperature of the cooling unit at above freezing because of the variations in its temperature with ambient temperature.

It is accordingly an'object of the invention to provide a defrosting mechanism for acooling unit compensated to maintain the refrigerated a mechanism shown in the defrosting position.

Referring to the drawing for a description of on embodiment of the invention, the reference numeral 8 designates an evaporator from which the refrigerant vapor is withdrawn through a tube 9 by a compressor l driven by an electric motor H, the compressor [0 andthe electric motor ll being housed in a sealed casing I2. The compressor l0 compresses the vapor drawn into the sealed casing l2 and forces the compressed vapor through a tube l4 into a condenser I3 wherein the refrigerant vaporis cooled and liquefied. From the condenser 13, the liquid refrigerant passes through a capillary tube I 6 to the bottom of the evaporator 8. The evaporator 8 is located in an insulated chamber l5 indicated by dotted lines in the drawing and is controlled by a switch I I to maintain the insulated chamber l 5 at a substantially constant temperature regardless of the temperature ambient the insulated chamber l5. The switch I! is locatedin a lead l8 which supplies the electric motor I l with electrical energy. Another lead I9 completes the 2 electric circuit of the motor.

Th switch I! is actuated bya bellows N which is subjected, through a tube 22, to the vapor preschamber at a substantially constant temperato the predetermined temperature.

Another object of the invention is to provide automatic means for terminating a defrostin cycle of a cooling unit when the defrosting thereof is completed.

A further object of the invention is to provide means for initiating a defrosting cycle for a cooling unit at timed intervals, and novel means for continuing the cycle until the defrosting of the cooling unit has been completed.

These and other objects are effected by my invention as will be apparent fromthe following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which 2 Fig. 1 is a schematic drawing of the defrosting mechanism of this invention applied to an evaporator of an evaporator:compressor-condenser refrigerating system, them'echanismbeing shown in the normalrefrigerating position but atthe point of starting the defrost cycle; and

Fig. 2 is a drawing similar to Fig; 1 but with sure of a volatile liquid (not shown) in abulb'23 in heat-conducting relationship with the air in the insulated cabinet [5. i The bulb 23 thus controls the refrigerating apparatus to maintain the air in the insulated chamber l5 substantially constant regardless of the heat loadthereon. If the heat load is high, such as occurs when the room in which the refrigerator is located is very warm, the bulb 23 will not shut off the motor ll until the evaporator 8 has been cooled to such a low temperature that it absorbs substantially all of the additional heat load which is being imposed on the insulated chamber E5. The temperature at which the bulb 23 maintains the evaporator B will thus vary inversely with the heat load on the refrigerator. Such a control is commonly referred to as a compensatingcontrol because it varies the average temperature of the evaporator to compensate for variations in the heat load. The bulb 23 is also in heat-conducting relationship with the evaporator Ill through a metallicheat-conducting strip 25. The strip 25 modifies the compensating features of the bulb 23 to prevent the evaporator 8 from assuming above freezing temperatures when the temperature of the air ambient the insulated; chamber I5 is relatively low. Italso prevents the evaporator 8 from assuming an excessively low temperature. As thus far described theapparatus is old and blade |8 in series with the switch H. The switch 24 7 comprises a switch blade 26 pivoted at one of ascaess its extremities On a stationary pin 21. The switch 26 is biased to the closed position by a spring 28. An upwardly-extending arm 29 is secured to the switch blade 26 adjacent the pivot 21 and is in the path of a circularly-swinging arm 3| driven by an electric clock mechanism 38 which obtains its power through leads 32 and 33 communicating, respectively, with the leads l8 and Ill. The electric clock mechanism 30 preferably swings the arm 3! at the rate of one revolution in 24 hours so that the defrosting switch 26 may .be opened once each night. An adjusting knob 34 on the clock mechanism 30 provides for setting the arm 3| to effect the opening of the switch 26 at the desired time.

The switch blade 26 is also provided with a downwardly-extending arm 36. A horizontal arm 31 pivoted at one end rests at its free end against the lower edge of .the arm 36 when the switch 26 is closed, the arm 31 being biased in that direction by a spring 38. The arm 31 is so located that, when the switch blade 26 is opened by the clock mechanism 30, the arm 31 will move upwardly under the action of spring 38 to rest against a pin 33 with the free end of the lever 31 engaging a side surface of the lever 36, thereby blocking the return of the lever 36 and holding the switch blade 26 in the opening position. This blocking or locking action of the arm 31 insures a continuance of the idle art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, andI desire, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

WhatI claim is: 1. Inv refrigerating apparatus, the combination of acooling unit. compensated control means for maintaining the temperature of the media in a chamber substantially constant regardless of the temperature of the media ambient the chamber, said cooling unit normally operating at mean temperatures below freezing, means for supplying said cooling unit with refrigerant, timed means for periodically effecting operation of the cooling unit at mean temperatures above freezing to defrost the same, and means responsive to the temperature of the cooling unit for again effecting operation thereof at mean temperatures below freezing when the temperature of the cooling unit has increased to a predetermined temperature above freezing temperatures.

2. In refrigerating apparatus, the combination of a cooling unit, compensated control meansfor maintaining the temperatureof the media in a chamber substantially constant regardless of the temperature of the media ambient the chamber, said cooling unit normally operating at mean temperatures below freezing, means for supplying said cooling unit with refrigerant, timed means for periodically effecting operation of the cooling unit at mean temperatures above freezing to defrost the same, and means responsive to the temperature of the cooling unitfor again effecting operation thereof at mean, temperatures period of the refrigerating mechanism 8, I2 and V I3 to insure complete defrosting of. the evaporator 8.

When the defrosting of the evaporator 8 is come pleted, the arm 31vis moved downwardly by a bellows 4| to release arm 36. The releasing of arm 36 permits the switch blade 26 to close under the action of spring 28, thereby again restoring the normal refrigeratingaction of the refrigerating mechanism 8, l2 and 3. The bellows 4| is actuated through a tube 42 by the vapor pressure of a volatile liquid (not shown) in a bulb 43 positioned in heat-transfer relationship with the evaporator 8. The melting of the frost on the evaporator 4| permits its temperature to rise above the freezing point, and the bellows 4| and spring 38 are so adjusted that the vapor pressure of the liquid in the bulb 43,

when above that temperature, overcomes the pressure of the spring 38 so that the bellows and the arm 31 is forced downwardly to release the arm 36.

It will be apparent from the above that the electric clock 30 initiates a defrosting period once each day, that the defrosting period is continued by the locking mechanism 36 and 31 until the evaporator I0 is defrosted, and that the defrosting cycle is terminated automatically when the defrosting of the evaporator is completed.

It will be further apparent that this defrosting device is adapted for use with refrigerating apparatus comprising a cooling unit compensated to maintain a refrigerated chamber at substantially constant temperature in spite of varying temperatures ambient the refrigerated chamber.

While I have shown my invention in but one i'orm,-it will be obvious to those skilled in the below freezing when the temperature of the cooling unit has increased to above freezing temperatures, said last means being independent and unaffected by the compensated control.

3. In refrigerating apparatus, the combination of a chamber, a cooling unit operating at below freezing temperatures for cooling said chamber, means for supplying said cooling unit with refrigerant, a device responsive to the temperature of the media in said chamber for rendering said supplying means periodically inactive to maintain the temperature of said media within predetermined limits, timed means for additionally rendering said cooling unit inactive, locking means for continuing the inactive period initiated by said timed means, and a second device responsive to the temperature of the cooling unit and independent of said first-named device for releasing said locking means when the temperature of the cooling unit has increased to above freezing temperatures. i I

4. In refrigerating apparatus the combination of a cooling unit normally operating at below freezing temperatures, means actuated by an electric motor for supplying said cooling unit means for releasing said sec-.

and switch from said locking means when the locking means when said cooling unit is above freezing temperatures.

6. In refrigerating apparatus, the combination of 'a cooling unit, means actuated by an electric motor for supplying said cooling unit with refrigerant, means for controlling said supplying means to maintain said cooling unit at below freezing temperatures, supply lines for supplying said electric motor with electrical energy, a switch in one ofsaid supply lines, clock mechanism for periodically opening said switch to initiate an inactive period of said motor, looking means for retaining said switch in the open position, and means indepedent of said controlling means for releasing said locking means when the temperature of said cooling unit is above freezing.

7. In refrigerating apparatus, the combination of a chamber, a cooling unit therefor, control means for said cooling unit to maintain the temperature of the media in said chamber substantially constant regardless of the temperature of the media ambient the chamber, said cooling unit operating normally at a mean temperature below freezing, means for supplying said cooling unit with refrigerant, timed means for periodically rendering said supplying means inactive to defrost the cooling unit, and means responsive to a predetermined temperature of the cooling unit to again render the supplying means effective.

- 8. In refrigerating apparatus, the combination of a chamber, a cooling unit therefor, control means for said cooling unit to maintain the 7 means effective, said last means being independcut and unaffected by said control means.

9. In refrigerating apparatus, the combination of a cooling unit, means for supplying said cooling unit with refrigerant, means for controlling said supplying means to maintain said cooling unit at below freezing temperatures, a

device for rendering said supplying means inactive, means for locking said device to continue the inactive period initiated by said supplying means, and means independent of said controlling means for releasing said locking means when said cooling unit is above freezing temperatures to return said refrigerant supplying means to the control of said controlling means.

10. In refrigerating apparatus, the combinaof a cooling unit, means actuated by an electric motor for supplying said cooling unit with refrigerant', means for controlling said supplying means to maintain said cooling unit at below freezing temperatures, supply lines for supplying said electric motor with electrical energy; a switch in one of said supply lines, a device for opening said switch to initiate an inactive period of said motor, locking means for retaining sai'd switch in the open position, and means independent of said controlling means for releasing said locking means when the temperature of said cooling unit is above freezing.

11. In refrigerating apparatus, the combination of a chamber, a cooling unit therefor, control means for said cooling unit to maintain the temperature of the media in said chamber substantially constant regardless of the temperature of themedia ambient the chamber, said cooling unit operating normally at a mean temperature below, freezing, means for supplying said cooling unit. with refrigerant, means for rendering said supplying means inactive to defrost the cooling unit, and means responsive to a predetermined temperature of the cooling unit to again render the supplying means active.

12. In refrigerating apparatus, the combination of a chamber, a cooling unit therefor, con- GRAHAM 8. McGLOY. 

